$f(x)=x^{3}3x^2-9x2$

$(1)$

Find $f^{\text{'}}(x)$

$(2)2.$ Find critical numbers

Use the first derivative test to find local extrema of $f.$

$(1)4.$ Find $f^{\text{'}\text{'}}(x)$

$(2)$

Use the second derivative test to find intervals where graph is concave up or concave down.

$(3)$

Find coordinates of the points of inflection.

$(4)$

Sketch the graph of $f$

Please solve and explain